1. Field of the Invention
The invention relates to a plant with several hydrocyclones which respectively feature an intake connection, an accepts connection, and a rejects connection for the heavy material.
2. Discussion of Background Information
As is known, hydrocyclones are used in order to fractionate liquids containing materials of different sinking behavior through strong centrifugal forces. Thus, it is possible, e.g., to concentrate contaminants contained in a fibrous suspension such as is used to produce paper and to discharge them from the hydrocyclone through a reject connection. The fraction freed from contaminants, i.e., the accepted stock, is drawn off through the accepts connection and used further. Moreover, hydrocyclone plants often also have the purpose of likewise removing at least most of the gases contained in the liquid, e.g., the air. To this end the accepted stock is placed under vacuum after leaving the hydrocyclone so that the gases emerge and can be drawn off separately. These processes are known per se, likewise the fact that a good effect is only ensured if the hydrocyclones do not exceed a certain size. With a hydrocyclone plant that is designed for larger throughput amounts, as is customary in paper factories, a plurality—often even a large number—of hydrocyclones is therefore required. These are then flowed through in a parallel manner by the liquid to be cleaned, which means that the liquid stream has to be divided into a number of smaller partial streams. To this end, e.g., distribution devices, as described below, can be used.
A plant is known from DE 41 06 140 A1 in which the accepts of a number of hydrocyclones are combined and guided into a deaeration chamber. In this they are divided through a perforated plate and then enter into a degassing volume kept under vacuum. The plant is very effective but requires a high expenditure in terms of equipment.
In other cases the pipelines that guide the accepts out of the hydrocyclones open into an accepts line to which the vacuum is applied. This accepts line is connected to a relatively large degassing container that is likewise under vacuum. One of this kind contains both a liquid phase and a gas phase. Examples of this are shown by U.S. Pat. No. 4,443,232 A, U.S. Pat. No. 5,236,475 A, EP 1 273 697 A and DE 17 61 496. These plants are particularly expensive because of the large degassing container and need a lot of space.